Posted: 8/23/2012 5:05:25 AM EDT
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Worth the cost? If so, what brands/types. "Buy once cry once" or "Six of one, half dozen of the other"?
I did a search and amazingly found nothing on the subject. I found a rubber-banded bundle of AA's from a recent expedition and have no idea if they're good. It got me thinking... Also, are there any that work with rechargables/alkaline as well as L-ion or (preferably) CR123A? Is a small, good multimeter a better alternative? Edited for format and to add one more question. |
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For our NiMH batteries, I use a LaCrosse BC-700 charger. It has a test mode that will charge, discharge, and measure capacity of your batteries. I've been using it to test some six year old Tenergy NiMHs and have found about half of them to still be good, with about 75-100% of their original capacity. About a quarter of the batteries read 0V and cannot be charged. This charger holds four batteries and charges each independently. When it's done, it displays the capacity of each independently, too. For alkaline batteries, you should see 1.5V on a fresh battery. A completely discharged alkaline should read about 1V or a little less. You can use a cheap multimeter set to 'DC Volts' to measure them. As a simple rule of thumb, just remember that you lose about 0.1V per 20% of charge: 100% = 1.5V 80% = 1.4V 60% = 1.3V 40% = 1.2V 20% = 1.1V 0% = 1.0V This isn't a perfectly accurate scheme, but it's easy to remember and useful. A cheap multimeter (or three) is an excellent investment. Learn to use the DC Volts, Ohms, and Continuity functions at the very least. Don't confuse Voltage and Current measurement modes or your meter will be short-lived. 
Lithium primary chemistry is a little different, and you may see more variability between different lots or makes of lithium cells. As a general rule, you can figure that a fresh cell will measure 3.2-3.3V. However, a nearly-depleted lithium cell will still show nearly full voltage until you apply a load to it, so for these a multimeter isn't the best choice for testing. I don't own a tester and just buy more cells when I start to run low. I use ~20 cells per year and keep at least 40 on hand, so I keep them rotated with no cell older than a few years. |
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another vote for multi-meter. You will find a MILLION uses for it. Tenma brand serve me well. The model I got came with a temp probe as well. ^^^Good source for electronics tools. They have good sales, so keep an eye out. ETA: While you are spending shipping at MCM, get yourself a good soldering iron or soldering station if you don't have one. |
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A cheap digital voltmeter. Harbor Freight sells one for a few bucks, but it doesn't automatically turn off.
Worth every penny, even my first grader uses mine. Digital allows you to check batterys in a drawer, or that have been stored for a while and tell almsot dead, from almost charged. Ditto, if you have something like a smoke detector, you can tell how much life is left, or if you change it, whether the old batteyr can still be used for other purposes. On the other hand, I would never use a $4 meter on high energy AC. Either use a good voltage detector or step up to once of the import brands marketed to tradesmen. Or buy a used analog meter-as long as the probers are in good shape. But there's a good reason most pros use fluke. |
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Yet another vote for a DMM.
Many of the clamp-on ammeters also have DMM functions - which gives you a very versatile instrument. My personal favorite is the Uni-T UT203, which not only measures voltage, resistance, frequency and AC current, but can also measure DC current - A feature that's almost unheard of in a 38 dollar clamp-on meter. 
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